1. Field of the Invention
The present invention relates to an apparatus for cooling a battery on an electric vehicle or the like which is propelled by an electric motor as a propulsion source that is powered by the battery.
2. Description of the Related Art
As well known in the art, a battery mounted on an electric vehicle or the like generates heat when it is charged or discharged. When the temperature of the battery rises due to the generated heat, the efficiency of the battery tends to be lowered or the battery tends to be degraded. Therefore, the battery needs to be cooled especially when it is charged in a quick charge mode.
To cool such a battery mounted on an electric vehicle or the like, the battery is associated with a cooling apparatus.
Attempts to cool a battery with a cooling apparatus include a proposal (hereinafter referred to as xe2x80x9cfirst technical proposalxe2x80x9d) disclosed in Japanese laid-open patent publication No. 5-344606 and a proposal (hereinafter referred to as xe2x80x9csecond technical proposalxe2x80x9d) disclosed in Japanese laid-open patent publication No.7-105988.
According to the first technical proposal, a battery on an electric vehicle is placed in an air-conditioning cycle of an air-conditioning system on the electric vehicle, and cooled by a refrigerant used in the air-conditioning system.
According to the second technical proposal, a portion of a water cooling passage of a battery is disposed in an absorption refrigerator to cool battery cooling water.
However, the first technical proposal is disadvantageous in that a refrigerant passage needs to extend into a battery box which houses the battery, making the battery box difficult to handle and also increasing the cost due to difficulty in installing a piping for the refrigerant passage.
The second technical proposal is also problematic in that the absorption refrigerator requires an additional installation space and increases the cost of the cooling apparatus.
It is therefore an object of the present invention to provide a vehicle battery cooling apparatus which is simple in structure and low in cost, and is capable of cooling a battery highly efficiently.
Another object of the present invention is to provide a vehicle battery cooling apparatus which is capable of providing an optimum cooling arrangement depending on the temperature of a battery to be cooled.
Still another object of the present invention is to provide a vehicle battery cooling apparatus which is highly reliable in operation.
According to the present invention, there is provided an apparatus for cooling a battery mounted on a vehicle, comprising first cooling means for cooling a cooling liquid to cool the battery with external air introduced by a fan, and second cooling means disposed adjacent to and in front of the first cooling means in a forward direction of the vehicle, for cooling the first cooling means with a passenger compartment air-conditioning apparatus on the vehicle.
Since the apparatus for cooling the battery is of a simple structure including the first cooling means for cooling the battery with external air and the second cooling means for cooling the battery with the passenger compartment air-conditioning apparatus, the apparatus needs a small installation space and minimizes any increase in its cost.
The apparatus also has temperature detecting means for detecting a battery temperature of the battery, and control means connected to the temperature detecting means and the first and second cooling means, for controlling operation of the first and second cooling means based on the battery temperature detected by the temperature detecting means. When the battery is charged in a quick charge mode, for example, the control means operates both the first and second cooling means, thus providing an optimum cooling arrangement depending on the battery temperature.
The control means comprises means for operating only the first cooling means to cool the battery when the battery temperature detected by the temperature detecting means is increasing and exceeds a predetermined reference temperature, and operating both the first and second cooling means to cool the battery when the battery temperature detected by the temperature detecting means is increasing further and exceeds a predetermined reference temperature higher than the above predetermined reference temperature. The apparatus is thus capable of efficiently cooling the battery with a power controllable depending on the battery temperature.
The first cooling means comprise a first heat exchanger disposed outside of a passenger compartment of the vehicle, for cooling the cooling liquid, and the second cooling means comprises a second heat exchanger branched from a refrigerant circulation passage of the passenger compartment air-conditioning apparatus and disposed outside of the passenger compartment. The apparatus for cooling the battery is thus of a simple arrangement.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.